Growing Cymbidium canaliculatum in Adelaide 1983 and Now

In 1983, Ron Robjohns, NOSSA’s first treasurer, wrote a comprehensive series of articles about growing epiphytes in South Australia. Thirty years on Ron’s information for growing is still helpful and applicable for today. Any updates or extra information are in black text.

NATIVE ORCHID SOCIETY OF SOUTH AUSTRALIA JOURNAL Volume 7, No. 11, December, 1983

GROWING EPIPHYTIC ORCHIDS IN SOUTH AUSTRALIA – R.T. Robjohns

Cymbidium canaliculatum

A most interesting orchid, also one of the few epiphytes to grow in Western Australia. It is credited with a southern limit of near Forbes in New South Wales, extending northwards to Cape Yorke Peninsula in northern Queensland and westwards across the Northern Territory to the northern areas of Western Australia. Although sometimes found in the near coastal areas of the eastern states it is primarily a plant of the open forests of the drier inland areas. In some of its habitats there is less than a 55 cm rainfall, summer temperatures of over 38⁰ C with a very low humidity and winter temperatures dropping to below freezing. While not exclusively, it is usually found growing in hollow branches or trunks of trees where its roots penetrate the decomposed wood and often grow to considerable length. No doubt the fact that the roots are protected from the heat enables it to survive and even thrive under such harsh conditions.

It frequently grows to form large clumps of crowded pseudobulbs having two to six leaves which are thick, rigid and channelled and are from 10 to 50 cm long and 2 to 4 cm wide. The racemes are up to 50 cm long and can be erect or pendulous with up to 60 extremely variable flowers about 2-3 cm across.

The colours range from green, brown, purple, dull red or a combination of those colours and may be either with or without spotting, the labellum, however, is usually white with red markings.

I find that C. canaliculatum responds reasonably well to cultivation and have grown and flowered it in plastic planters filled with a mix of charcoal, pine bark and rotted hardwood, also in hollow logs filled with the same mixture. Propagation from backbulbs has been with limited success and it looks like about a six year project from planting to flowering.

An established plant can take full sun and will withstand our winter frosts without detriment. Fertilising has been with the occasional dose of liquid fertiliser. When purchasing from a nursery I would suggest medium to small plants as although large clumps may look attractive they usually have had the root system almost completely removed – an operation to which they do not take kindly.

Cym caniculatum drawing

Les adds that Cym. canaliculatum should be kept dry from Anzac Day (25th April) to September when the flower spikes appear.

Growing Epiphytic Orchids in Adelaide 1983 and Now

In 1983, Ron Robjohns, NOSSA’s first treasurer, wrote a comprehensive series of articles about growing epiphytes in South Australia. Thirty years on Ron’s information for growing is still helpful and applicable for today. Any updates or extra information are in black text.

NATIVE ORCHID SOCIETY OF SOUTH AUSTRALIA JOURNAL

Volume 7, No. 3, April, 1983

GROWING EPIPHYTIC ORCHIDS IN SOUTH AUSTRALIA – R.T. Robjohns

Epiphytes usually grow where there is plenty of air movement, ample light but also shade and to achieve this they are frequently found well above the ground storey in the forest from where, should they be dislodged from their host and fall to the forest floor they wither and die. With most plants the roots grow downwards, however, with epiphytes in their natural habitat, the roots may grow up, down or around their host, that is, in any direction in search of suitable conditions.

As a novice grower I urge you to learn all you can about the natural habitat of the plant and its principal host, bearing in mind that in accounts of plants that grow on rock faces, often they are growing with their roots in crevices into which any moisture drains and maybe in an accumulation of leaf litter. Frequently the rocks on which the lithophytic orchids grow are sandstone – a rock which can absorb moisture and consequently keeps cool longer than most other rocks. “In an exposed situation” should not be construed as being in full sun all of the time: usually they receive some shade.

With the possible exception of Cymbidium canaliculatum few epiphytes grow at their best in full sun in nature. Full sun in the hot dry South Australian summer will usually burn off the plants or at the best cause severe yellowing and loss of leaves. It is to be noted that this State has no native epiphytic orchids.

Most Australian epiphytic orchids grow in the coastal belt of northern New South Wales and Queensland where the average rainfall in their DRY season is much the same as the Adelaide winter or WET season with which it coincides, consequently advice that plants require to dry out during the winter should not be taken to the extreme and the plants left without water.

The three principal requirements of epiphytes are a free air circulation, a semi-shaded position and free drainage.

In South Australia epiphytes are grown in two ways, the most popular being pot culture and the other slab culture.

For pot culture the medium must be a free draining one and a mixture of “aged” pinebark, scoria and charcoal is quite effective.

Note 2015 – Today the potting media used is composted pine bark.  Charcoal is not used and scoria can get cold and wet in winter.

In choosing material for slab culture consider the conditions under which you intend to grow the plants. For humid conditions cork is ideal while tree fern, which holds moisture longer, is good for dry conditions, although any of our native trees with papery or corky bark is suitable. Perhaps you would wish to attach the plants directly to trees in your garden, for this purpose try Jacaranda, Melaleuca or trees with a similar bark.

Watering is important, slab culture requires more watering than pot culture and in summer water orchids on slabs at least every second day and every-day during a hot spell. Water according to the weather and watch for signs of stress – in wintertime the rain is usually sufficient.

Fertilising is best done using half of the recommended strength of commercial proprietary fertilisers.

As a last general recommendation – beware of frosts. Last year (1982) the frosts in some areas of Adelaide caused severe losses amongst plants of epiphytic native orchids. Large tubs of D*. speciosum, whose thick leathery leaves I mistakenly thought frost resistant, were reduced to a mass of leafless canes; even baskets of D. kingianum hanging three feet below the 50% shadecloth had all of the leaves burnt off. These were but two of the varieties which suffered, so be warned and ensure that your plants are protected from frosts.

*D. = Dendrobium

Dendrobium speciosum
Dendrobium speciosum in culture